He is a nail that will not bend - wrote Oleg Sentsov in his letter right out of Siberia. He is serving a 20-year prison term. In 2014 Sentsov was arrested in Crimea and accused of plotting terror acts. This is his first letter, smuggled out of jail. Sentsov denounces Russia's "cowardly" war in Ukraine – a war in which Moscow maintains it isn't a participant.

"For three years I've been sitting in a Russian prison. For those three years a war has been conducted against my country," Sentsov writes. "The enemy is fighting like a coward, vilely, pretending he's has nothing to do with this. Nobody believes it. But that doesn't stop him."